1. Field of the Invention
The invention relates generally to rolling tarp systems, and, more specifically, to rolling tarp systems provided on trucks or trailers transporting cargo to be covered with the tarp. Preferred embodiments comprise a bar system that is added to a rolling tarp that improves the consistency and effectiveness of the rolling process.
2. Related Art
Conventional truck beds or trailers for hauling of farm products or other bulk cargo are frequently equipped with a tarp adapted to cover the open top of the bed or trailer. The tarp may prevent significant loss of cargo during travel at highway speeds, and also may prevent the cargo from becoming wet from rain during travel or temporary storage in the bed/trailer. Such conventional tarps are typically rolled-up to reveal the open top of the bed/trailer for loading of cargo, and then unrolled to cover the open top.
Many conventional rolling tarps are adapted to roll in a direction that is transverse to the length of the truck bed or trailer, and are frequently called “side-rolling” tarps. Such side-rolling tarps are typically provided on truck beds or trailers that are substantially box-shaped, wherein all four vertical sides of the “box” are generally the same height. In such beds/trailers, the unrolled tarp is substantially horizontal, as it extends generally between two horizontal side edges of the bed/trailer that are at the same elevation. Therefore, the entire rolling process is substantially horizontal rather than vertical, and the total length of tarp that must be furled is approximately equal to the transverse width of the bed/trailer.
Side-rolling tarps powered from a single end are ineffective, and therefore typically not used, on beds/trailers that have a significantly lower side, such as trailers adapted to receive “blow-in” produce such as silage. In such conventional “low-sided” bed/trailers, one side is several feet lower than the opposite side and the front and rear ends, so that farm product may be generally horizontally “blown-in” to the bed/trailer over the low side. Said opposite side connects to a partial roof that extends at an upward angle over about half of the bed/trailer to form a roof peak. The blown-in product is stopped, and/or contained, by said opposite side, the partial roof, and the front and rear ends, during loading of the product. The same partially-open, partially-closed roof system, without a side-rolling tarp, helps to contain the product/cargo during transport to some extent, but is problematic and less than optimal at highway speeds.
Such low-sided beds/trailers typically have elongated span members (“bows”) that are transverse to the length of the bed/trailer and spaced apart at multiple locations along the length of the bed/trailer. The bows are spaced apart far enough to allow the product to be blown in or otherwise easily loaded into the bed/trailer. The bows typically extend from at or near the roof peak of the partial roof generally horizontally to a position above the low side, then bend about midway along their length to form bow corners generally above said low side, and then extend down to connect to said low side. The bows may be used to support a tarp or other covering over the open top of the bed/trailer and/or may contribute structural strength to the bed/trailer.
If a conventional side-rolling tarp, powered from a single end of the bed/trailer, were provided on a low-sided bed/trailer, the proximal end of the tarp would be secured to the bed/trailer at or near the roof peak. The tarp would unroll generally horizontally (slightly downward) along the upper portion of the bows and then would extend generally vertically down the vertical portions of the bows toward the low side, against which the tarp distal edge would be secured. A Shurlock™ latch system, ties, latches, or other systems could be used to secure the distal edge to the low side. The rolling-up process would begin, therefore, at or near the low side edge, and the tarp would have to roll generally vertically upwards to the corners of the bows, and then would continue to roll “up-hill” to near the peak of the roof. Substantially the entire process would therefore be “up-hill.” This process, powered from one end of the bed/trailer, has been attempted and has been shown to be unacceptably difficult and inaccurate. The roll becomes very non-uniform along its length, with the end near the power source being tight, and the opposite end being loose and sloppy. This non-uniformity typically exhibits itself by the time the roll reaches the bow corners, and becomes so extreme that such side-rolling tarps are conventionally understood to be ineffective on such low-sided beds/trailers.
Therefore, there is still a need for an improved rolling tarp system. The invention meets this need, and, in preferred embodiments, provides a simple and economical system for solving or limiting the previous problems exhibited by rolling tarps. Preferred embodiments provide a system for consistent and tight rolling of a tarp even on a low-sided farm produce trailer or truck bed, as discussed above, which previously has been a particular problem in the industry. Instead of using a rigid metal partial roof to partially cover a low-sided trailer and/or using an ineffectively/inaccurately-furled tarp or other cover, a side-rolling tarp according to embodiments of the invention may be retracted, for loading of cargo/produce, to about the peak of the tarp roof in a consistent and controlled rolling method previously not achievable in tarps powered from a single end of the tarp. Thus, the preferred embodiments of the tarp bar allow a low-sided trailer to be fitted with a side-rolling tarp, rather than a rigid metal partial roof, for covering the trailer during transit, but wherein the tarp may be retracted to about the peak of the tarp roof in a consistent and controlled rolling method.